검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 25

        1.
        2022.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate infrared properties of OGLE4 Mira variables in our Galaxy. For each object, we cross-identify the AllWISE, 2MASS, Gaia, and IRAS counterparts. We present various IR two-color diagrams (2CDs) and period-magnitude and period-color relations for the Mira variables. Generally, the Mira variables with longer periods are brighter in the IR fluxes and redder in the IR colors. In this work, we also revise and update the previous catalog of AGB stars in our Galaxy using the new sample of OGLE4 Mira variables. Now, we present a new catalog of 74,093 (64,609 O-rich and 9,484 C-rich) AGB stars in our Galaxy. A group of 23,314 (19,196 O-rich and 4,118 C-rich) AGB stars are identified based on the IRAS PSC and another group of 50,779 (45,413 O-rich and 5,366 C-rich) AGB stars are identified based on the AllWISE source catalog. For all of the AGB stars, we cross-identify the IRAS, AKARI, MSX, AllWISE, 2MASS, OGLE4, Gaia, and AAVSO counterparts and present various infrared 2CDs. Comparing the observations with the theory, we find that basic theoretical dust shell models can account for the IR observations fairly well for most of the AGB stars.
        4,200원
        3.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study is to evaluate the asphalt binder properties using FTIR analysis. METHODS : To investigate the chemical properties of asphalt binders, FTIR tests were performed. Recently, FTIR was used for quantification under various aging conditions. Three scans were averaged for each sample within the wavenumber range of 4000 to 400 cm-1, at a resolution of 4 cm-1 (default Simatech software settings). To determine the oxidation of the extracted asphalt binder and the remaining TCE solution in the extracted asphalt binder, the penetration test was adopted and compared. To track the changes in the chemical composition of the aged bitumens, the ATR spectrum of each sample was analyzed, both qualitatively and quantitatively. The qualitative analysis involved identifying characteristic absorption peaks for the functional group of interest, such as polymer components, carbon and sulfur oxidation products, and polar aromatics. RESULTS : The asphalt binder is easily oxidized in air during FTIR testing. To reduce the oxidization of the asphalt binder, the asphalt binder must avoid air contact to measure constant results. Sometimes, the extracted asphalt binder has a residual solvent (TCE), which affects the evaluation of the extracted asphalt binder rheology, such as absolute viscosity and penetration testing. To solve this problem, the research team adopted the FTIR test method. First, the TCE was scanned with FTIR to obtain the chemical characteristics of TCE. After that, the extracted asphalt binder was scanned and the FTIR spectra were compared with those of TCE. If there is a TCE in the extracted asphalt binder, a typical peak was found in the spectrum. Thus, it is possible to estimate the content of the TCE remaining in the extracted asphalt binder via the FTIR test method. CONCLUSIONS : It is possible to evaluate the aging of asphalt binder through FTIR analysis used for the analysis of the chemical structure of asphalt. In addition, during FTIR analysis, the sample is required to avoid air contact to obtain accurate results. FTIR analysis was conducted to confirm whether the solvent (TCE) remained in the extracted asphalt binder and it was confirmed that the penetration increased by a factor of two when the solvent remained. This suggests that it is difficult to control the quality of the asphalt mixture by controlling the amount of recycled additive, as well as the aging of the extracted asphalt binder.
        4,000원
        4.
        2019.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate the characteristics of self-assembled quantum dot infrared photodetectors(QDIPs) based on doping level. Two kinds of QDIP samples are prepared using molecular beam epitaxy : n+-i(QD)-n+ QDIP with undoped quantum dot(QD) active region and n+-n−(QD)-n+ QDIP containing Si direct doped QDs. InAs QDIPs were grown on semi-insulating GaAs (100) wafers by molecular-beam epitaxy. Both top and bottom contact GaAs layer are Si doped at 2×1018/cm3. The QD layers are grown by two-monolayer of InAs deposition and capped by InGaAs layer. For the n+-n−(QD)-n+ structure, Si dopant is directly doped in InAs QD at 2×1017/cm3. Undoped and doped QDIPs show a photoresponse peak at about 8.3 μm, ranging from 6~10 μm at 10 K. The intensity of the doped QDIP photoresponse is higher than that of the undoped QDIP on same temperature. Undoped QDIP yields a photoresponse of up to 50 K, whereas doped QDIP has a response of up to 30 K only. This result suggests that the doping level of QDs should be appropriately determined by compromising between photoresponsivity and operating temperature.
        4,000원
        5.
        2018.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the properties of infrared photodetectors based on two kinds of quantum dots(QDs): i) 2.0 ML InAs QDs by the Stranski-Krastanov growth mode(SK QDs) and ii) sub-monolayer QDs by 4 × [0.3 ML/1 nm In0.15Ga0.85As] deposition(SML QDs). The QD infrared photodetector(QDIP) structure of n+-n−(QDs)-n+ is epitaxially grown on GaAs (100) wafers using molecular-beam epitaxy. Both the bottom and top contact GaAs layers are Si doped at 2 × 1018/cm3. The QD layers are grown with Si doping of 2 × 1017/cm3 and capped by an In0.15Ga0.85As layer at 495 oC. The photoluminescence peak(1.24 eV) of the SML QDIP is blue-shifted with respect to that (1.04 eV) of SK QDIPs, suggesting that the electron ground state of SML QDIP is higher than that of the SK QDIP. As a result, the photoresponse regime(~9-14 μm) of the SML QDIP is longer than that (~6-12 μm) of the SK QDIP. The dark current of the SML QDIP is two orders of magnitude smaller value than that of the SK QDIP because of the inserted Al0.08Ga0.92As layer.
        3,000원
        6.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Presently, the number of known asteroids is more than 710,000. Knowledge of size and albedo is essential in many aspects of asteroid research, such as the chemical composition and mineralogy, the size-frequency distribution of dynamical families, and the relationship between small bodies in the outer solar system or comets. Recently, based on the infrared all-sky survey data obtained by IRAS, AKARI, and WISE, the large asteroid catalogs containing size and albedo data have been constructed. In this paper, we discuss the compositional distribution in the main belt regions based on the compiled data on size, albedo, and separately obtained taxonomic type information.
        3,000원
        9.
        2014.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 보리의 취반 적성과 관능성 개선을 위하여 수침처리 및 적외선 가열조건의 영향을 검토하였다. 보리의 수분흡수도는 적외선가열 단독처리 또는 수침과 적외선가열의 병행처리 모두에서 크게 증가하였으며, 취반 후보리의 연화도 또한 증가하였다. 또한 이들 시료를 백미와 혼합하여 취반 후 관능성을 평가한 결과, 식감의 개선에의한 보리의 전체 기호도가 대조구 보다 크게 개선되는 것을 확인하였다. 또한 수침과 적외선가열을 병행 처리하였을 때 적외선가열 단독처리보다 우수한 관능특성을 갖는것으로 조사되어, 보리의 취반성과 관능성 개선을 위한 최적조건은 15분간 상온수침 후 120oC에서 초기 수분함량까지 가열로 설정하였다.
        4,000원
        10.
        2013.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Fe4[Fe(CN)6]3 coated on a mica or TiO2/mica surface as infrared reflective blue pigment was prepared by a hydrothermal method. Fe4[Fe(CN)6]3, used as coloring agent, was uniformly coated on mica or TiO2/mica under the optimized condition of a 1.2 : 1 weight ratio between iron(III) chloride hexahydrate and potassium ferrocyanidetrihydrate at the initial pH level of 4.5 at 70˚C. The infrared (IR)-reflective pigments were characterized by SEM, Zeta-potenial, FT-IR, and UV-VIS NIR spectrophotometry. Especially the CIE color coordinate and total solar reflectance(TSR) properties of the pigments were investigated in relation to variation of the coating and coated substrate thicknesses. Isolation-heat paint was prepared with 20 wt% blue pigments fully dispersed in acryl-urethane resin and several additives to coat the film uniformly. The films were also measured with CIE color coordinate, TSR, and the surface temperature was recorded by an isolation-heat measuring system. The pigments and films of Fe4[Fe(CN)6]3 coated on mica and TiO2/mica showed high TSR values compared with the TSR value of Fe4[Fe(CN)6]3 itself. According to the increase of TSR value, the property of isolation-heat is effective. To realize the optimal blue color, we applied the the pigment to TiO2 coated mica(TM(b)) which has blueish interference color. The pigment of Fe4[Fe(CN)6]3 coated on TM(b) shows a strong blue color compared with that of Fe4[Fe(CN)6]3 coated on TiO2/Mmca(TM(w)), which has a whitish interference color.
        4,000원
        11.
        2013.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 현미의 취반적성 및 관능성 개선을 위하여 적외선 가열처리 및 수침의 영향을 검토하였다. 현미는 적외선 가열처리 조건에 따라 부분적인 갈변화와 함께 외피 및 배유에 균열이 발생하여, 취반 후 곡립 형태가 파손되고 식미가 저하되었다. 현미의 균열 손상은 120oC 이상의 온도에서 초기수분함량이 3% 이상 감소할 때까지 가열하는 조건에서 발생하였으나, 수침과 병행하여 가열하는 경우에는 현미의 균열 및 형태 손상이 발생하지 않았다. 현미는 적외선 가열에 의해 부분 호화가 발생하며, 호화도는 수침 처리한 현미에서 더 높은 것으로 확인되었다. 현미는 적외선 가열 처리에 의해 취반 질감이 연화되었으며, 수침과 병행하는 경우 가장 높은 연화효과를 나타내었다. 취반 현미의 관능성은 적외선 가열 처리에 의해 크게 개선되었으며, 수침을 병행하였을 때 전체적인 기호도가 가장 높은 확인되었다. 상기 결과를 통하여 수침 처리하지 않은 현미의 경우 120oC에서 수분함량이 1% 감소까지, 수침시료의 경우 20분간 상온수침 후 110oC에서 수분 함량 14%까지의 가열조건을 현미의 취반성과 관능성 개선을 위한 최적조건으로 설정하였다.
        4,000원
        12.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We will report our recent study on the properties of more than 1,600 galaxies detected by the AKARI All-Sky Survey with physical quantities based on optical and 21-cm observations, to understand the physics determining the infrared spectral energy distribution (Totani et al., 2011). We discover a tight linear correlation for normal star-forming galaxies between the radiation field strength of dust heating (corresponding to dust temperature) and the galactic-scale infrared radiation field, LTIR/R2 . This is the tightest correlation of dust temperature ever known, and the dispersion along the mean relation is 13% in dust temperature. This relation can be explained physically by a thin layer of heating sources embedded in a thicker, optically-thick dust screen. We also find that the number of galaxies sharply drops when galaxies become optically thin against dust-heating radiation, indicating that a feedback process to galaxy formation (e.g., by the photoelectric heating) is working when dust-heating radiation is not self-shielded on a galactic scale. We discuss implications from these findings for the MHI -size relation, the Kennicutt-Schmidt relation, and galaxy formation in the cosmological context.
        4,000원
        13.
        2012.09 KCI 등재 구독 인증기관·개인회원 무료
        We established a separation scheme to distinguish galaxies from stars with the aid of AKARI/FIS color-color (CC) diagrams. In all the combinations of CC diagrams we can distinguish two separate clouds. It was shown that in all cases one of them contains more than 95% of galaxies and the other one, in most cases, consists in more than 80% of stars (Pollo et al., 2010). Currently we are looking into more detailed classifications. We are especially interested in separating different morphological types of galaxies, mainly within spiral galaxies. Moreover, we study the properties of infrared galaxies.
        14.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigate the mid-infrared (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the infrared survey catalogs of AKARI, IRAS and WISE. Out of 135 non-blazar AGNs in the Swift/BAT 9-month catalog, we obtain the MIR photometric data for 128 sources in either the 9, 12, 18, 22, and $25{\mu}m$ band. We find a good correlation between their hard X-ray and MIR luminosities ranging three orders of magnitude (42 < log λLλ(9,18 μm ) < 45), which is tighter than that with the FIR luminosities at 90 μm . Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori models rather than homogeneous ones.
        4,000원
        15.
        2012.09 KCI 등재 구독 인증기관·개인회원 무료
        We present the properties of dust and the near-infrared spectral features in nearby early-type galaxies. The properties of dust are obtained from the AKARI far-infrared all-sky survey diffuse map. The AKARI/IRC is used for the near-infrared spectra. We improve spectral data with the new dark subtraction method on the basis of the knowledge acquired in our laboratory experiments of the engineering-model detector for the IRC. We have succeeded in fitting the continuum by a power-law function and detecting CO and SiO absorption features in early-type galaxy spectra. Comparing the properties of dust and near-infrared spectral features, we find that the power-law slope depends on dust temperature, but not on the dust mass, which suggests that low-luminosity AGNs may contribute to the changes in the power-law slope and dust temperature.
        17.
        2010.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In order to study properties of the pulsation in the infrared emission for long period variables, we collect and analyze the infrared observational data at L band for 12 OH/IR. The observation data cover about three decades including recent data from the ISO and Spitzer. We use the Marquardt-Levenberg algorithm to determine the pulsation period and amplitude for each star and compare them with results of previous investigations at infrared and radio bands. We obtain the relationship between the pulsation periods and the amplitudes at L band. Contrary to the results at K band, there is no difference of the trends in the short and long period regions of the period-luminosity relation at L band. This may be due to the molecular absorption effect at K band. The correlations among the L band parameters, IRAS [12-25] colors, and K band parameters may be explained as results of the dust shell parameters affected by the stellar pulsation. The large scatter of the correlation could be due to the existence of a distribution of central stars with various masses and pulsation modes.
        4,200원
        18.
        2008.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present optical and near-infrared imaging and long-slit spectroscopy for the blue compact dwarf galaxy (BCD) Mrk 49 in the Virgo Cluster. The surface brightness distribution analysis shows that Mrk 49 consists of an off-centered blue bright compact core of r = 10′′ and a red faint outer exponential envelope. The Hα image and color difference suggest that these two components have different stellar populations: a high surface brightness population of massive young stars and an underlying low surface brightness population of older stars. The redder near-infrared colors of the inner most region suggest that the near-infrared flux of Mrk 49 originates from evolved massive stars associated with the current star-forming activity. The total apparent magnitude is BT = 14.32 mag and the mean effective surface brightness is μeff (B) = 21.56 mag arcsec−2. Long-slit spectroscopy shows that Mrk 49 rotates apparently as a solid body within r = 10′′ in a plane at position angle 55 degrees with an amplitude of about 20 km sec−1. The measured radial velocity of Mrk 49 was derived as 1,535 km sec−1; and the total mass of stars and gases is in the range of 3 to 6 × 109 M⊙. The mass-to-light ratios for the central region of Mrk 49 in I and B band are estimated 1.0 and 0.5, respectively. The upper limit of the dark matter to visible matter ratio seems to be < 5. The oxygen abundance is 12 + log(O/H) = 8.21 ± 0.1 which is about one quarter of the solar value while the relative helium abundance appears to be similar to that of the sun.
        5,100원
        20.
        1999.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Pt/SiOz!Si의 기판위에 (Pb,La)TiO3(PLT) 박막을 졸-겔 방법으로 제작하여 La 첨가량 및 후속열처리 온도에 따른 결정학적, 전기적 특성율 조사하였다. 600˚C 이상의 온도에서 열처리된 PLT 박막 시료의 경우 La 도핑량에 관계없이 전형적인 perovskite 결정구조를 보여 주었다. La이 전혀 첨가되지 않은 (Pb,La)TiO3(PT) 시료에 10 mole% La을 첨가할 경우 (PLT-I0 시료) c축 배향도는 약 63%에서 26%로 크게 감소하였다. PLT-1O 박막시료의 깊이에 따른 AES 분석결과 박막내의 각 성분원소 들이 비교척 균일하게 분포되어 았고 하부전극(Pt)과 PLT 박막층 사이에는 상호반응없이 비교적 안정된 막을 형성하고 있음을 알 수 있었다. 600˚C에서 열처리된 PLT-1O 박막의 유전상수(εr) 와 유전정접 (tanδ) 은 약 193과 0.02의 값을 나타내였다. 후속열처리 온도를 600˚C 에서 700˚C로 증가함에 따라 잔류분극(2Pr,Pr+-Pr-)은 약 4μCcm2 에서 약 16μCcm2로 크게 증가하였으며 잔류 분극값의 증가는 후속열처리에 의해 결정성이 개선되었기 때문이라 판단된다. 30˚C 온도부근에셔 초전계수(γ)는 약 4.0nC/cm2·˚C의 값을 냐타내었다.
        4,000원
        1 2